﻿// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
// Copyright (c) 2011, Dr. Masroor Ehsan
// All rights reserved.
// 
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//     * Redistributions of source code must retain the above copyright
//       notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above copyright
//       notice, this list of conditions and the following disclaimer in the
//       documentation and/or other materials provided with the distribution.
//     * Neither the name of the author nor the
//       names of its contributors may be used to endorse or promote products
//       derived from this software without specific prior written permission.
// 
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
// DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// 
// $Author: masroore@gmail.com $
// $Id: AbstractEventsBroker.cs 34 2011-10-21 07:30:34Z masroore@gmail.com $
// $Rev: 34 $
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

using System;
using System.Collections.Generic;

namespace MaxTrader.Core.Events
{
    public abstract class AbstractEventsBroker<T> : IObservable<T> where T : class, new()
    {
        private readonly object _lock;
        private readonly List<IObserver<T>> _monitors;

        public AbstractEventsBroker()
        {
            _monitors = new List<IObserver<T>>();
            _lock = new object();
        }

        #region IObservable<T> Members

        public virtual IDisposable Subscribe(IObserver<T> monitor)
        {
            lock (_lock)
            {
                if (!_monitors.Contains(monitor))
                {
                    _monitors.Add(monitor);
                }

                return new Unsubscriber<T>(this, monitor);
            }
        }

        #endregion

        internal void RemoveMonitor(IObserver<T> monitor)
        {
            lock (_lock)
            {
                if (_monitors.Contains(monitor))
                    _monitors.Remove(monitor);
            }
        }

        public virtual void Dispatch(T value)
        {
            lock (_lock)
            {
                foreach (var observer in _monitors)
                    observer.OnNext(value);
            }
        }

        public virtual void TearDown()
        {
            lock (_lock)
            {
                foreach (var observer in _monitors)
                    observer.OnCompleted();

                _monitors.Clear();
            }
        }
    }
}